base64常用的前缀(excel,doc,pdf,png,jpg)
.doc——data:application/msword;base64,
.docx——data:application/vnd.openxmlformats-officedocument.wordprocessingml.document;base64,
.xls——data:application/vnd.ms-excel;base64,
.xlsx——data:application/vnd.openxmlformats-officedocument.spreadsheetml.sheet;base64,
.pdf——data:application/pdf;base64,
.ppt——data:application/vnd.ms-powerpoint;base64,
.pptx——data:application/vnd.openxmlformats-officedocument.presentationml.presentation;base64,
.txt——data:text/plain;base64,
.png——data:image/png;base64,
.jpg——data:image/jpeg;base64,
.gif——data:image/gif;base64,
.svg——data:image/svg+xml;base64,
.ico——data:image/x-icon;base64,
.bmp——data:image/bmp;base64,